The present invention relates to a process for the depositing, onto a substrate, of a coating mainly constituted of an electronic conductor compound.
According to one of the techniques known up to now, such a coating is formed by reactive cathode sputtering, also known as xe2x80x9creactive sputteringxe2x80x9d. Such a process especially presents the disadvantage of a comparatively low deposition speed, resulting from the contamination of the used targets from which the pulverization is achieved.
Another known technique is the activated evaporation in a vacuum, called ARE (Activated Reactive Evaporation). This technique also has to cope with a problem of contamination of the evaporation system, which considerably reduces the efficiency of the depositing.
One of the essential aims of the present invention is to propose a process of the above-mentioned type, allowing to realize, at a high speed, a coating on a substrate, electrically conducting or not, and this essentially of a relatively significant thickness.
It concerns, more particularly, a process of mass production of layers of electrically conducting compounds with a thickness of the order of 1000 xc3x85 on a substrate formed, for example, of drawn steel, flat glass, a sheet of paper or a plastic film.
For this purpose, according to the invention, the said coating is formed by producing alternatively, on the one hand, in at least one depositing zone, one or several deposits of a determined thickness of an electronic conductor element, such as a metal, an alloy, a semi-conductor of the N-doped type, on the substrate, and, on the other hand, in at least one reaction zone, one or several reactions of the element thus deposited with the ions of a reactive gas which are implanted into the deposit of the aforesaid element approximately over the entire determined thickness in such a way that the said compound is formed with approximately the majority and preferably with the total quantity of this element, the aforesaid ions being submitted to a kinetic energy below 2000 V; preferably from 200 to 900 V, while the above-mentioned thickness of the deposit of the element is determined as a function of the applied kinetic energy in such a way that the implantation of these ions can be achieved over approximately this entire thickness.
Advantageously, the above-mentioned reaction of the element deposited on the substrate with the above-mentioned reactive gas is accomplished by creating, facing and in the proximity of the surface of the latter presenting the deposit of the element, a plasma in which the above-mentioned reactive gas is introduced, in such a way that ions are formed in it, penetrating into the deposit of the element, approximately over a depth corresponding to the thickness of this deposit in order to have them react with the deposited element.
According to a particular embodiment of the invention, a negative potential with regard to an anode is applied to the substrate, in the reaction zone.
According to an advantageous embodiment, the depositing of the element by evaporation, preferably in a vacuum, is followed by a condensation onto the substrate.
According to a particularly advantageous embodiment, the deposit of the element on the substrate is formed by cathode sputtering.
According to a preferred embodiment of the invention, on the substrate a coating is formed, consisting of a layer of a ceramic electronic conductor compound, for example a compound of the TiN, ZrN, TiCN, CrN, VN, NbN, InSnO type, which is obtained by the reaction of at least one metal and one reactive gas, by accomplishing first, in the depositing zone, a deposit of the said metal on the substrate, and thereafter, in the reaction zone, an ionization of the gas, in a plasma, formed facing this deposit, and an implantation of ionized particles of this gas into the metal deposit, a negative potential with regard to the ionized gas being applied to the latter.
The invention also concerns a particular device for the use of the above-mentioned process.
This device is characterized in that it includes at least one depositing zone in which a deposit of an electronic conductor element may be formed on the substrate, this depositing zone being followed by at least one reaction zone, separated from this depositing zone, where an implantation may be accomplished, into the aforesaid deposit, of particles which may react with this element in order to form the electronic conductor compound, means being provided for moving, preferably in a continuous way, the substrate from the depositing zone to the reaction zone.
Other details and characteristics of the invention will appear from the description given below, by way of unlimitative examples, of a few particular embodiments of the invention with reference to the appended figures.